162306a36Sopenharmony_ci.. SPDX-License-Identifier: GPL-2.0 262306a36Sopenharmony_ci 362306a36Sopenharmony_ci============================================ 462306a36Sopenharmony_ciThe proc/net/tcp and proc/net/tcp6 variables 562306a36Sopenharmony_ci============================================ 662306a36Sopenharmony_ci 762306a36Sopenharmony_ciThis document describes the interfaces /proc/net/tcp and /proc/net/tcp6. 862306a36Sopenharmony_ciNote that these interfaces are deprecated in favor of tcp_diag. 962306a36Sopenharmony_ci 1062306a36Sopenharmony_ciThese /proc interfaces provide information about currently active TCP 1162306a36Sopenharmony_ciconnections, and are implemented by tcp4_seq_show() in net/ipv4/tcp_ipv4.c 1262306a36Sopenharmony_ciand tcp6_seq_show() in net/ipv6/tcp_ipv6.c, respectively. 1362306a36Sopenharmony_ci 1462306a36Sopenharmony_ciIt will first list all listening TCP sockets, and next list all established 1562306a36Sopenharmony_ciTCP connections. A typical entry of /proc/net/tcp would look like this (split 1662306a36Sopenharmony_ciup into 3 parts because of the length of the line):: 1762306a36Sopenharmony_ci 1862306a36Sopenharmony_ci 46: 010310AC:9C4C 030310AC:1770 01 1962306a36Sopenharmony_ci | | | | | |--> connection state 2062306a36Sopenharmony_ci | | | | |------> remote TCP port number 2162306a36Sopenharmony_ci | | | |-------------> remote IPv4 address 2262306a36Sopenharmony_ci | | |--------------------> local TCP port number 2362306a36Sopenharmony_ci | |---------------------------> local IPv4 address 2462306a36Sopenharmony_ci |----------------------------------> number of entry 2562306a36Sopenharmony_ci 2662306a36Sopenharmony_ci 00000150:00000000 01:00000019 00000000 2762306a36Sopenharmony_ci | | | | |--> number of unrecovered RTO timeouts 2862306a36Sopenharmony_ci | | | |----------> number of jiffies until timer expires 2962306a36Sopenharmony_ci | | |----------------> timer_active (see below) 3062306a36Sopenharmony_ci | |----------------------> receive-queue 3162306a36Sopenharmony_ci |-------------------------------> transmit-queue 3262306a36Sopenharmony_ci 3362306a36Sopenharmony_ci 1000 0 54165785 4 cd1e6040 25 4 27 3 -1 3462306a36Sopenharmony_ci | | | | | | | | | |--> slow start size threshold, 3562306a36Sopenharmony_ci | | | | | | | | | or -1 if the threshold 3662306a36Sopenharmony_ci | | | | | | | | | is >= 0xFFFF 3762306a36Sopenharmony_ci | | | | | | | | |----> sending congestion window 3862306a36Sopenharmony_ci | | | | | | | |-------> (ack.quick<<1)|ack.pingpong 3962306a36Sopenharmony_ci | | | | | | |---------> Predicted tick of soft clock 4062306a36Sopenharmony_ci | | | | | | (delayed ACK control data) 4162306a36Sopenharmony_ci | | | | | |------------> retransmit timeout 4262306a36Sopenharmony_ci | | | | |------------------> location of socket in memory 4362306a36Sopenharmony_ci | | | |-----------------------> socket reference count 4462306a36Sopenharmony_ci | | |-----------------------------> inode 4562306a36Sopenharmony_ci | |----------------------------------> unanswered 0-window probes 4662306a36Sopenharmony_ci |---------------------------------------------> uid 4762306a36Sopenharmony_ci 4862306a36Sopenharmony_citimer_active: 4962306a36Sopenharmony_ci 5062306a36Sopenharmony_ci == ================================================================ 5162306a36Sopenharmony_ci 0 no timer is pending 5262306a36Sopenharmony_ci 1 retransmit-timer is pending 5362306a36Sopenharmony_ci 2 another timer (e.g. delayed ack or keepalive) is pending 5462306a36Sopenharmony_ci 3 this is a socket in TIME_WAIT state. Not all fields will contain 5562306a36Sopenharmony_ci data (or even exist) 5662306a36Sopenharmony_ci 4 zero window probe timer is pending 5762306a36Sopenharmony_ci == ================================================================ 58